The present invention relates to a pneumatic tire, more particularly to a tread pattern capable of improving noise performance.
In general, tires for winter use such as snow tire designed for running on snowy roads are provided in the tread portion with a block pattern in order to improve on-snow performance. In such block pattern tires, however, due to the pitch sound and pumping sound, noise performance when running on pavements such as well paved asphalt roads is not good.
On the other hand, the Japanese Patent Application Publication No. 2012-011981 (corresponding to US-2012-000586A1) discloses a pneumatic tire which is as shown in FIG. 4 provided with a crown circumferential groove (a) disposed on each side of the tire equator C, a shoulder circumferential groove (b) disposed on the axially outside of each of the crown circumferential grooves (a), crown lateral grooves (d) extending between the crown circumferential grooves (a), middle lateral grooves (e) extending between the crown circumferential grooves (a) and the shoulder circumferential grooves (b), and shoulder lateral grooves (f) extending between the shoulder circumferential grooves (b) and the tread edges Te, wherein each of the circumferential main grooves (a) and (b) is a zigzag groove extending in a trapezoidal waveform, and parameters such as the zigzag amplitude and groove width of each main groove, the number of the lateral grooves in the ground contacting patch of the tire, and the groove width of the lateral grooves are specifically defined in order to improve the mud performance without sacrificing the noise performance.
Even if this tire is useful as a snow tire to some extent, namely, when used on muddy melted snow, the noise performance is still not satisfactory in recent demand for low noise snow tires.